Rotary pump



Feb. 28,1950 F. A. WHITELEY 2,498,972 ROTARY PUMP Filed Dec.- 4, 1944 I2 Sheets-Sheet 1 Fig. I

IN VEN TOR.

Feb. 28, 1950 F. A. WHITELEY ROTARY PUMP Filed Dec. 4, 1944 2Sheets-Sheet 2 Patented Feb. 28 1950 UNITED STATES PATENT OFFICE2,498,972 a Y ROT UMP Frank A. Whiteley, Minneapoli s, Minn. 7Application December 4, 1$i44,' Serial No. 566,519 I 13 Claims. (01.236- 152) My invention relates to low vacuum high pressure rotary pumps,and has for its Object to pro- .vide a rotary pump having radiallymovable cylindrical or other shaped pistons, operated by ,a rotoreccentrically positionedwithin a cylinder,

wherein the surfaces of the movable pistons, contacting surfaces of therotor and of the inside walls of the cylinder, are continuouslysubjected to an oiling action of oil delivered at high pressure.

The well known rotary pump, when used either for producing vacuum orcompression, has many advantages over other forms of pumps, such, forexample, as reciprocating piston pumps. This is due to its continuousrotary motion, eliminatl.

'fing many friction and inertia losses inherent in such other typesofpumps, in consequent large savin of power over them, and in'resultingvery .great decrease of bulk and size in proportion to the powerconsumed and the volume of 'fiuid evacuated or compressed.

But a serious diificulty hasbeen encountered in the use of rotary pumpson gas Where a'high jvacuum or a high degree of compression is're-"quiredJ Thisis that leakage of the gas may take place from the highpressure'side to the low pressure side of the pump. Many efforts to-overcome this difiiculty haveb'een made, but the appliances for doingit, oiling appliances for example, have not been really effective forthe purpose, and in most of these effortsfha'v'eadded so fmuch in bulkand power consumption as to largely "nullify the advantages of using arotary pump. It is a primary purpose of my invention'to adapt a rotarypump of the type shown in my Patent No. 2,352,748 to the production-of avery high vacuum, as 1% to lb. per square inch, with a resultingdifierential between the low pressure and high pressure sides of thepump of up .to '150 lbs. per square inch. I have discovered that thiscan be done by circulating a very small amount of oil past certainadjacent fixedand 'movab1e surfaces of the'pump proper at much higherpressures, such as up to 300 lbs. per square foot, aided by connectingthe spaces at the rear jof the radially movable pistons with the high pressure side of the pump, and with independent return of the circulatedoil fromthe two sides of the pump to the oil pump so as to effectivelyblock communication between the high pressure and lower pressure sidesof the vacuum pump. I It is a principal object of my invention, there-;fore, to provide a rotary pump having a cylinifdrical pumping chamber,with parallel end walls,

\ n whichis eccentrically mounted for rotation a rotor formed with oneor more longitudinal radial slots opening at the ends of each slot tothe end walls, and with a piston member movable radiallyin each slot,together with means for forcing oil at high pressure .into the spacesbetween the end walls and the ends of the pistons.

It is a further object of my invention to provide ayrotary pump having acylindrical chamber with parallel end walls and to mount eccentricallytherein a cylindrical rotorwith an element thereofin close engagementwith the inner surface of the chamber, and to form a slot or a number ofslots, equally spaced and longitudinally extending in the rotor openingto the end walls, with piston members in said slots having. their endfaces engaging the said end walls, and further to mount an oil pumpoperated by the same meansfthat' operates the rotor withconnectionstherefrom'to efiect delivery of oil at very high pressure to the spacesbetween the end faces of the rotorand pistons and the end walls of thechamber.

It is a further object of my invention to pro- .vide a' gear oil pumpwith two gear couples re,-

ceiving return oil from the high pressure and lower pressure sides ofthe rotary pump and del'ivering the oil at high pressure to a commonchamber, with all communication between the high pressure and lowpressure sides of the rotary pump blocked by the respective gearcouples.

' It is a further object of my invention to provide passages forconveying th high pressure oil ,directly to the space between an endwall of the rotary pump chamber and the adjacent end faces in the twoend Walls of the gas pumping chamber circular slots concentric to thecylindrical walls ,of 'the gas pumping chamber, to mount a high pressureoil pump on one of said end walls,

with oil inlet ports connected independently with the high pressure andthe low pressure sides of j the gas pump, and with direct connection ofthe h outlet high pressure side of the oil pump with one of saidcircularslots, and to connect the two slots -fo'r oil delivery from one toanother by longitudinal passages through the pistons, which passagewa'ysare at all times held to center on-the respective slots, whereby at alltimes high pressure oil is delivered to the spaces between the end walls.of the pumping chamber and the sets 3 of end walls of the rotor and thepiston or pistons.

It is a further object of my invention to have continuous connection ofthe inner parts of the rotor slots with the high pressure side of thegas pump, both to permit discharge of oil and gas from the back of theslots and also to maintain a constant pressure on the backs of thepistons to hold them firmly in contact with the cylinder walls and to.push the oil fed down at the junction of piston walls with the slotWalls into the space between them with a considerable degree ofpressure.

The full objects and advantages of my invention will appear inconnection with the detailed description thereof, as given in theappended specification, and the novel features by which the aforesaidadvantageous results are obtained will be particularly pointed out inthe claims, it bein understood that the particular form of rotor andpistons here shown and claimed may be varied without'departing from thescope of my invention.

In the drawings illustrating an application of my invention in one ofits forms:

Fig. 1 is a longitudinal sectional view of my invention taken on line l!of Fig. 2.

Fig. 2 is a transverse sectional view taken on line 2.2 of Fi 1.

Fig. 3 is a'transverse sectional view across, the pumping cylinder onlytaken on line 33 of Fig. 1 and viewed in the direction of the arrows.

Fig. 4 is a transverse sectional view of the invention taken on line 4-4of Fig. 1.

Fig. 5 is a transverse sectional view of the invention taken on line 55of Fig. 1.

Fig. 6 is a transverse sectional view taken on line 66 of Fig. 1, viewedin the direction of the arrows.

Fig. 7 is a transverse sectional view taken on line l'l through the endcasting viewed in the direction of the arrows.

Fig. .8 is a partial sectional transverse view taken through the pumpingcylinder and parts therein only, corresponding to the similar parts ofFig. 2 showing application of my invention of a different form ofpiston.

As illustrated, referring to. Figs. 1 and 2, 2. rectangular outer casingis provided formed of heavy sheet metal which comprises side walls Itand H, end walls 12 and I3, and a top wall M. In the form of theinvention shown, this casing is as indicated and is supported in avertical position by any suitable means (not shown), al-

. though the invention may be effectively embodied where the casing hasits longest extent horizontal.

Within the above noted casing is fixedly mounted a cylinder l5 havingits walls of substantial thickness and its inner surface 16. polished toa true and smooth cylindrical surface. cylinder is secured at H and I8to the side walls to and H by welding or other suitable means so as tomake a gas-tight joint therewith and divide This the space within thecasing into two chambers 19 and 20, of which chamber 19 is divided intotwo smaller chambers 2i and 22 by an upright partition 23, Fig. 2, whichterminates as indicated in dotted lines at 24%, Fig. 1, short of the topof chamber [9. The respective chambers 2| and 22 are, therefore,connected at their top, but are separated by gas-tight sealing ofpartition 23 to casing end wall l3 and cylinder [5. A gas inletpassageway 25, Fig. ,1 admits gas to chamber 20,

. the passageway 25 connecting with any source of V supply of gas (notshown) either for creating Vacuum in a chamber, not shown, or forfeeding for compression in the chamber 19 and the chambers 2i and 22connected therewith. Whether the device is used for creating high vacuumor for compressing, gas chamber [9 and connected chambers 2i and 22 areat the high pressure side of the gas pump and chamber 29 is at the lowpressure side of the pump. A series of openings 26 extend through thewalls of cylinder [5 into chamber 28. Through these openings the air orother gas being evacuated or compressed enters the pumping cylinder foraction of the pump. Also through these openings is discharged the oil,the pumping of which under high pressure makes up a major part of myinvention. This oil is thrown out through the openings 26 against theinner surfaces of walls it, I l and I2 and gravitates to the bottom ofchamber 20 where it passes through openings 2? and 23 to the oil sump29, later to be described.

Other sets of apertures 38 lead through the cylinder it; into chamber 2!substantially below the top of partition 23. The evacuated air or othergas as it is being compressed or driven against the pressure ofatmospheric air goes through these openings into chamber 2| where it isthrown against the walls i9, i3 and 3 and gravitates to the bottom ofchamber 2! going therefrom through an opening 3!, Figs. 1 and 2 into oilsump 32, later to be described. The compressed gas or the gas evacuatedat the low pressure side of the gas pump thus goes first into theoil-receiving chamber 2! and then rises to spill over the edge ofpartition 23 into chamber 22, from whence it leaves through aperture 32,Fig. 2, to be discharged out of the system. Aperture 32 may be connectedto suitable piping (not shown) to convey the gas thus moved to anydesired point for discharge to atmosphere; or, for example, to asuitable gasometer for holding the compressed gas.

In the example shown, formed in conjunction with an upper shaftextension 33 and a lower shaftv extension 34 is a pump rotor 35 which isin the form of a cylinder having milled therein a series (in the exampleshown 3) of long slots 36, 37 and 38. This constitutes the elementreferred to in the specification and claims as the pumping rotor orsimply as the rotor.

In the form illustrated, the slots 36, 3'! and 38 are made of a size toreceive respectively a series of rollers 39, 4t and il, Fig. 2, whichrollers operate in a well known way within the cylinder {5 as in effectpumping pistons, for which reason they are referred to herein aspistons. There are certain advantages in a pump, of the above describedtype in having these pistons in the form of cylinders, since it gives arolling contact with the smooth inner wall of the cylinder, thuspreventing friction, and the relatively broad curve of the contactportions of these pistons with the inner wall of the cylinder,particularly with the means of forcing the pistons intofirm engagementwith these walls by reason of the slots being connected with the highpressure side of the gas pump, insures a very firm oil I seal at thepoints of contact of the piston and gaging the side walls Of the slotsand with outer faces preferably somewhat curved to-g-ive better contactwith the inner wall of the cylinder.

The rotor has its outer walls ground and polished to a, smoothcylindrical surface. It is of less diameter than the inner diameter ofcylinder l5 and is eccentrically mounted within said cylinder so itsouter walls will engage the inner walls of the cylinder tangentiallyalong an element of each. This leaves a crescent-shaped space, indicatedat 44 of Fig. 2, in which the piston members 39, and 4| operate, beingcaused by rotation of the rotor to follow with their outer limits andcontact the inner surface of the cylinder l5 so that the crescent-shapedspace is successively divided between each pair of pistons into lowpressure and then high pressure chambers, receiving gas from the lowpressure chamber 20 and driving the relatively compressed gas into thehigh pressure chamber 2|. This operation has long been known as also hasthe use Of cylindrical pistons and I make no claim to invention inrespect to these features here described, except as they are modified instructure and arrangement for effecting the purposes and accomplishingthe results of my invention.

In the vertical mounting of the rotor, herein disclosed, the shaftsection 33 extends through an opening in a top plate 46 through a ballbearing assemblage 4T resting on top plate 46 and held in a recess in asecond plate 48. The surface of plate 46 which contacts the uppersurface of cylinder I5 and said upper cylinder surface, are milledsmooth and true as are the contact surfaces of members 46 and 48. Theentire assemblage is held together in gas-tight relation by a suitablenumber of screw bolts 49, Figs. 1 and 6. A stuffing piece 56 of standardconstruction is formed on the top of plate 48 for effecting a gas-tightseal about shaft extension 33. At the bottom of the cylinder I5 issecured a heavy piece 5| which has 'a cylindrical portion 52 thatextends within the cylinder l5 and is provided with a ledge part 53milled true and smooth which engages the lower end of cylinder l5 and isheld to it gas-tight by means of a suitable number of screw bolts 54,Figs. 1 and '7. The piece 5| has extending through it an opening 55 forreceiving the lower shaft extension 34. A plan view of the upper part 52of the piece 5| is shown in Fig. 3.

Referring to Figs. 1 and 3, a circular channel 56 is cut in the uppersurface of the extension 52 which, as the rotor 35 is mounted within theI cylinder I5, is eccentric to the center of the rotor, but concentricwith the circular cross-section of the inside of the cylinder. Thecylinder pistons 39, 40 and 4| are of a diameter in reference to thedepths of the slots 36, 3'! and 38 so they will.

not reach the bottoms of the slots in their most retraced position andwill not have their diameters extended beyond the outer limits of theslots in their most projected positions. Centrally through each of theroller pistons 39, 40 and 4| is formed a bore or passageway 51 of adiameter equal to the width of the channel 56, and this passagewaythrough each and all of the cylindrical pistons at all times travelsalong and directly above the channel 56. Likewise these passagewaystravel along a circular channel 58 formed to open out of the top piece48. The channels 56 and 58 are identical in width and depth and are bothof quite considerable depth. It follows that ifoil under highpressurface of the cylinder chamber.

sure is delivered to the channel 56'it will also continuously bedelivered through the passageways 51 to the upper channel 58 and thisoil under high pressurewill be continuously forced from the channels 56and 58 between the upper and lower end faces of the rotor and theJcylindrical pistons and the respective upper and lower plates or plateportions 46 and 52 so that the moving faces of the rotor and piston endswill always be traveling along and upon a film of high pressure oil andthus will efiectively block any tendency for leakage of gas from thehigh pressure to the low pressure sides of the pump- As shown in Figs. 1and 3, and l and 6, another circular groove is cut in each of the .topand bottom plates designated respectively as groove 59in the portion 52of plate 5| and groove 68 in the top plate 46. These grooves arecircular surrounding respectively the lower shaft 34 and'the upper shaftsection 33. From groove 59 is cut a tubular downwardly extending hole 6|which communicates'with a lateral passageway 62. The passageway 62, asclearly shown in Figs. 1, 3 and '7, opens directly into an elongatedaperture 63 extending through the wall of cylinder l5 into chamber 2|.This is on the high pressure side of the gas pump. In practice severalsuch connections as the vertical and horizontal passageways 6| and 62may be made to give ample area for the discharge of oil from the backportions of slots 36, 31 and 38, all of which at all times overlie thecircular groove 59, as clearly shown in Fig. 2. The angularly disposeddouble tubular passageways 6| and 62 are made necessary so' as not toconnect the circular channel 56 with the circular channel or groove 59,which would result in rapid flooding of the pressure oil from the oilpump, hereinafter to be described.

As shown in Figs. 1 and 6, from the channel 60 is a similar verticaltube 64 which connects with a horizontal tube 65, indicated in dottedlines in Fig. 6. Here again several of such passageways 64, 55 may beemployed to fully open the groove 68 directly to the high'pressurechamber l9.

This will permit thefree flow of gas from the pressure Side through thepassageway or passageways 65, 64 and the circular channel or groove 60into the rear ends of rotor slots 36, 31 and 38, thus subjecting thebacks of the pistons 39, 4|] and 4| continuously to the pressure of thegas at the high pressure side.

That would mean that if the apparatus were used, for example, toevacuate air to produce a very high vacuum of say to A of a pound per 1square inch, that the differential of air pressure in the high pressureside transmitted to the grooves 36, 31 and 38, and from the grooves tothe back of the pistons 39, 46 and 4|, as against the low pressure side,would be up to lbs., which at all times will insure firm contact oftheouter margins of the piston against the inner This is particularlyimportant with the rolling contact which will take place in connectionwith the use of cylindrical pistons such as shown. The pressure in theslots back of the pistons opposed to the low pressure side, which is theonly place where gas leakage is likely to occur, will force the oil intothe channels I05 wedge-shaped in cross-section at the sides of theroller pistons or channels I06 similarly wedge-shaped in cross-sectionalong the sides of the straight wall pistons and withthe high oilpressure employed will effectively prevent any cross leakage of gas.

The oil pump is shown in Figsl, 4 and 5. Here aif i si 'm a lowerhousing member 66. and a separator plate 6.1 above it having true flatcontacting surfaces, are held together in gas-tight relation by screwbolts 68 threaded at suitable points of separation into the bottom pieceThe bottom piece 5| has formed therein the oil sump chambers 28 and 32,Fig. l, and a connecting channel 69. From the channel 69 are formed pumpgear housing chambers m, H, 12 and 13. Within housing 10 is a pump gear14 which extends. into. the connecting channel 69 and meshes across saidchannel with a pump gear which is in the. gear chamber '13 and whichextends into channel 69 to mesh with pumpgear 1.4-. Within gearhousingchamber H is a pump gear 15 which extends-into connecting channel 69 andmeshes. with a pump gear 11' in gear housing chamber J12, the; gears 76and H meshing across said connecting channel 619 The pump gear 14 isfast on the drive shaft ex? tension 34 and is driven directly by themain drive shaft. The pump gear 75 is. fast on a bearing shaft 18. Thehousing member 86. has formed therein a chamber 1 9. just belowseparator plate 61 and on the shaft 34; is a drive gear 8B which mesheswith a drive gear 81 fast on a shaft 82 upon which is mounted the spurgear l5, as clear- 1y shown in Figs. 1 and 5. The gears 80 and :84 havethe same diameter. The pump gear l6; and drive gear 8| are onthe commonshaft 82. Hence the pump gear 15 has the same rate of rotation as thepump gear 1-4. and since pump :gear '16 meshes with pump gear 11 whichis mounted on bearing shaft 83, the pump gears 15 and 11 will rotate atthe same rate as the pump gears 14 and 15.

The several pump gears rotate in the direction oft-he arrows (seeFig.4). Itwill be noted that the inlet side of the gear couple of gearsM and T5 is open to the oil sump 32 and. the inlet side of the gearcouple made. up of gears L6 and H is open to the oil sump 28. The oilsump 32- receives return oilfrom the high pressure .side of the gas pumpand the oil sump 28 receives oil from the low pressure-side. Therespective gear couples, therefore, block all pressure communicationbetween the high pressure side and thelow pressure side.

Both gear couples: discharge the oil into the center part of the'chamber' 69' where itisdelivered at high. pressure. It discharges. fromthe chamber through a discharge bore 8'4, shown in longitudinal extentin thetop memberfii Fig. and in transverse outline in Figs; 4- and 7; Asshown in Fig. '7, the bore 84 extends into the annular channel so thatthe high pressure oil goes directly from chamber vS9 through the shortbore 84 into the annular channel 55.

From this annular. channel the high pressure oil will spread between thelower surface of the rotor 35 and the upper surface ofrthe plate exten-.sion 52, and it will also spread betweenthe upper surface of said plateand all thelower surfaces of the rollers 39, 46 and 41.

The oil from theannular channel; 56 will. also be forced upward throughall of the bores 5? in the centers'of the pistons '39, 4'91 ands' ll.From the top of-each ofthese bores the oil will bed'elivered to theannular channel 58 in. top-plate 46 from which it will be forcedbetween: the lower surface of said top plate and the upper surfacesofthe piston rollers39, 38 and 41' and the upper surface of the rotor35. A bore 85 leads. through top, plate 46 to communication with thechamber 86 of the ball bearing 41, which thus receives. a

- constant supply of oilfrom the annular channel 5.8' to keep the upperball bearings 41 properly lubricated,

A thrust ball bearing 81 is. mounted in a chamher 83 within head member66 for supporting fiorfree rotation therotor and the upper shaftextension 33 and lower shaft extension 34 thereof. Oil is delivered tochamber Hi housing the drive gears and 81 through a small port 89, seeFigs. 1 and 5, which keeps, the chamber l9 filled with oil for oilinggears 89.. and 8|, and likewise keeps the chamber 88 for the thrustroller bearings prop y ile There will, of course, be a very small amountof oil pumped through the system and that. at high pressure. This. willrequire an adaptation of: the oil pump. gear couples and variouspassageways in size such as to make possible the movement of therequisite amount of oil at. the hi h pressure emanded.

Astufifing box- !lll, Fig. l, seals the shaft 3,5. in gas-tight.condition.

Where rectangular pistons, such as are shown in Fig. 8 are employed theannular grooves 5E and 59 in lower plate extension 52 and the annulargrooves 58, and. 66 in the top plate 46 and all connections thereto;will be identically the same as where the cylindrical pistons areemployed. In thev non-cylindrical pistons there will be bores of whichwill registerat their respective ends with the annular channels .56 and58. In this. form of piston there Will, of course, be. no rotation butsince the; channels. 56 and 58, are concentric with the inner wall ofthe cylinder hi it. is obvious that, they will always register withsaid, channels.

The oil level will be maintained at substantially the top surface 92 ofthe ledgepart 53. of the piece 5|". Gauges 9 3 and 94 are provided,gauge '93 connecting as indicated in dotted, lines at 95 with the lowerpart of oil sump 32 and connecting as indicatedin dotted lines at 96with the chamber 2.1. A screw :cap 91 sealing the gauge gas-tight may beopened for supplying moreoil. Similarly, the gauge 94 opens, asv shownin'dotted lines;at'99 tot'he lower part of oil sump 29 and opens,as'indicated in dotted lines at me, into the chamber 20. The gas-tightscrew cap closure Hil may be removed to permit addition of oil. The oil:level whenv the pump is at rest -W0uld. be somewhat. higher than thelevel 92,

dropp to that level as the discharge; of oil through the different.parts of the apparatus takes up. a considerable part of the oil in thetwo/separated sumps. Somewhat more oil will go back into the oil sump 32onthe-highv pressure sidethan goes into the sump. 28 on the low pressureside, but substantially all loss of oil will be on the high pressureside where the compressed gasispushed out of'chamber 22; for whichreason the levels on the two sides, that is above oil: sump 32 and oilsump 28, will remain substantially constant.

Theadvantages 'of'my invention follow directly from the structure andcombination of elements hereinbefore described. In operation the highpressure oil will be constantly forced between the contacting surfacesof the rotor and pistons on the-one hand. and of the end cylinder wallson the other. A certain amount of this oil will be forced through thesmall space between these sets of end' walls and at the top thereof willgravitate down the pistons themselves. Where the roller pistonsareemployed this oil will, by the rotation of these pistons, constantly bedrawn into the wedge-shaped contact space between the walls of the rotorslots; being forced inwardly at one side of the rotor and outwardly atthe other side. The oil will thus'be caused to pile up in these.wedge-shaped contact portions and effectively seal gas-tight against anyleakage of gas past the contacting elements of the. piston walls withthe cylinder and slot walls.

A fundamental advantage of my invention, considering the resultseffected by it, is its extreme simplicity. Everything is in effecthoused in a single casing. The gear pump is driven simultaneously withthe drive of the rotor and by the same means. The oil channels, both forpressure oil and for discharge of oil from the rear ends of the slots,can be made by a simple milling operation and all oil-conductingchannels are short and direct. All moving parts are constantly travelingin oil. Friction is thus reduced to the smallest minimum. Maintaining ofthespecial connection back of the pistons with the high pressure side ofthe gas pump keeps the roller pistons in their extended position andprevents any tendency for them to be pushed back while the piston ismoving through the compression or high pressure side of the pump.

While three pistons are shown in the example" illustrated and described,it will be obvious that any number of pistons may be employed from oneup, without departing from the scope of my invention.

Also, although the roller pistons ,are shown solid with bores drilledthrough their centers, it will be obvious that these roller pistons maybe tubes, as in my aforesaid Letters Patent, with internally-positionedtubes or channels openin at the centers of plates sealing the ends ofsuch an elongated piston member in each of said slots having its endsengaging said end walls, means for rotating said rotor and all of the'pistons therewith, means continuously connecting the inner ends of allof the slots with the high pressure side of the pump while the rotor.is. being rotated, and means including circular channels in said endwalls and a passageway through each of the pistons registering with saidchannels for forcing and conducting oil at high pressure into the spacebetween the two end walls of the rotor and the piston and said end wallswhile the rotor is being rotated. l

2. In combination with a rotary pump embodying a pumping chamber and arotor and pistons in the pumping chamber for moving gas therethrough andcompressing it while. ,being moved, passages for high pressure gas andlow pressure gas respectively on opposite sides of and in communicationwith the pumping chamber, means for pumping oil at high pressure tocontacting parts of the rotor, pistons and pumping chamber, comprising aseparate sump independentlylconnected with each passage for receivingreturn oil, a separate gear pump couple for moving oil from each sumpwhile blocking pressure communication between the, sumps, a space formedbetween the couples for receiving the oil pumped by both couples, andmeans including a passageway directly from the space for conducting theoil underpres'sureto parts ofthe rotor and pistons contacting'the wallsof the'chamber. 3. A rotary pump; comprising a cylindrical pumpingchamber having parallelend walls with a circular channel in each endwall concentric with the inner walls of the chamber, a rotor and pistonsin the chamber having their ends in substantial contact with the endwalls, passages for high pressure gas and low pressure gas respectivelyon opposite sides of and in communication with the pumpingv chamber, aseparate sump independently connected with each passage for rei ceivingreturn oil, a separate gear pump couple for moving oil from each sumpwhile blocking pressure communication between the sumps, a space formedbetween thecouples for receiving the oil pumped byboth couples, andmeans including a directpassageway from the space and communicating.with one of said circular chan- 20 nels and including a passagewaythrough at least one piston registering with both channels forconducting highpressure oil to 5 the spaces between ,the ends of rotorsand pistons and the end walls.

, .4. A rotary pump, comprising a cylindrical pumping chamber and havinga rotor and pistons in the chamber with parts thereof in contact withwalls of the chambenpassages for high pressure gas and low pressure gasrespectively in opposite sides of and in communication with the chamber,a separate sump independently connected with each passage for receivingreturn oil, a drive shaft for the rotor, a'separate gear pump couple formoving oil from each sump while blocking pressure communicationbetweenthe sumps, a gearof one couple'being fast on said shaft, a drivegear on the shaft for driving the other couple, a space formed betweenthe couples for receivingtheoil pumped by both couples, and

, a direct passageway from said space for conveying high pressure oilbetween contacting parts of the gas pumping mechanism with walls of thepump cylinder. 1 I

' 5. In a rotary pump, a cylindrical pumping chamber having parallel endwalls, an eccentrically positionedrotor therein formed with alongitudinal slot opening to'said end walls, a piston member in saidslothaving its ends engaging said walls, means for rotating said rotor andpiston, an oil feeding.channel extending through said piston and openingat its ends in the planes of said end walls, the ends of said channelsin the Operation of thedevice moving in circles. ecceni trio tothecenterof..the rotor, circular slots in the end walls; correspondinglyeccentric to the center of the rotor so as ,to come. over theends.of'said. piston openings at all times, and a single means forfeedingoil under pressure ,into one ,of said circular slots whereby saidpressure oil will .be. fed through thepiston openings tothe other nelsin. the operation of the device moving in circles eccentric to thecenter of the rotor, circular slots in the end walls correspondinglyeccentric to the center of the rotor so as to come over the ends of thesaid piston openings at all times, a

pump chamber having a single opening leading to one of said slots, andmeans operated by the rotor-operating means for delivering oil underpressure to one of said circular slots, whereby oil under pressure willbe delivered through the pis- -ton opening to the other of said slotsand will be forced in a high pressure film between the ends of the rotorand of the piston into said end walls while the rotor is being driven.

'7. A rotary pump, comprising a casing forming a cylindrical pumpingchamber having parallel end walls, passages for low pressure gas andhigh pressure gas respectively on opposite sides .said end walls,correspondingly positioned oil openings extending through each of saidpistons,

the ends of said openings being caused to travel in a circle eccentricto the center of the rotor, circular slots in the end walls opening tothe ends of said oil openings in all positions of all of the pistons,and means for forcing oil under high pressure into one of said circularslots whereby through the openings in the pistons said pressure oil willbe forced into the other of said circular slots and oil be distributedin a pressure film between the ends of the rotor and of the pistons andsaid end walls.

8. A rotary pump, comprising a casing forming a cylindrical pumpingchamber having parallel end walls, passages for low pressure gas andhigh pressure gas respectively on opposite sides of and in communicationwith the pump chamber, an eccentrically positioned rotor having its endssubstantially engaging said end walls, a

multiplicity of longitudinal slots in said rotor opening to said endWalls, a cylindrical piston member in each of said slots With the endfaces of each piston member in close proximity to said end Walls, an oildelivering opening through the center of each piston, a circular slot ineach of said end walls, said circular slots coming over the oildelivering piston openings in each position thereof, and a source of oilunder high pressure having a connection with one of said slots, wherebysaid pressure oil will be delivered to the other of said slots throughsaid center oil deliveringopenings and a pressure film of oil will bemain-' tained between the ends of the rotor and of the pistons and therespective end walls.

9, A rotary pump, comprising a casing form- 1 ing a cylindrical pumpingchamber having parallel end walls, passages for low pressure gas andhigh pressure gas respectively on opposite sides 1 delivering passagewaythrough the center of each piston, a circular channel in each of saidend walls, said circular channels coming over the oil delivering pistonopenings in each position thereof, a pumping chamber having connectionwith one of said circular channels, a pair of pumps delivering oil athigh pressure to said. pumping chamber and simultaneously operated bythe means for operating the rotor, said oil pumps respectively openingto the high pressure side and the low pressure side of the rotary pump,whereby high pressure oil is delivered through the central oil openingsfrom one circular channel to the other circular channel and isdistributed as a high pressure film over the ends of the rotor and ofthe pistons and the respective end walls.

10. A rotary pump, comprising a cylindrical pumping chamber havingparallel end walls, passages for high pressure gas and low pressure gasrespectively open to opposite sides of the pumping chamber, aneccentrically positioned rotor in the pumping chamber formed with aplurality of longitudinal slots opening to said end walls, a pistonmember in each of said slots having its ends engaging said walls, meansfor rotating said rotor and piston, means for supplying a high pressurefilm of oil between the ends of the rotor and of the pistons and saidend walls, and a circular passageway having connection with each of saidslots and with the high pressure side of the pump for permitting thedrainage of oil accumulating in said piston holding slots and formaintaining a constant pressure against the backs of all said pistons.

11. A rotary pump, comprising a vertically positioned cylindrical pumpand chamber having parallel top and bottom walls, passages for lowpressure gas and high pressure gas respectively on opposite sides of andin communication with the pumping chamber for conveying the low pressuregas and discharging the high pressure gas after compression thereof, arotor and pistons in the pump chamber for moving the gas therethroughand compressing it, while being moved, an oil sump having gravityconnection with the low pressure side and a second oil sump havinggravity connection with tlie high pressure side, and a two part gearpump between the sumps, one part having pumping connection with the oilin the low pressure sump and the other part having connection with thehigh pressure sump.

12. A rotary pump, comprising a vertically positioned cylindrical pumpand chamber having parallel top and bottom walls, passages for lowpressure gas and high pressure gas respectively on opposite sides of andin communication with the pumping chamber for conveying the low pressuregas and discharging the high pressure gas after compression thereof, arotor and pistons in the pump chamber for moving the gas there throughand compressing it while being moved, an oil sump having gravityconnection with the low pressure side and a second oil sump havinggravity connection with the high pressure side, two gear pump coupleseach independently moving oil from a different sump While blockingpressure communication therebetween, said couples discharging oil athigh pressure into a common space between them, and means including apas sageway from said space for conducting said high pressure oil to thespaces between the ends of the rotor and pistons and said end walls.

13. A rotary pump, comprising a vertically positioned cylindrical pumpand chamber having parallel top and bottom Walls, passages for lowpressure gas and high pressure gas respectively on opposite sides of andin communication with the pumping chamber for conveying the low pressuregas and discharging the high pressure gas after compression thereof, arotor and pistons in the pump chamber for moving the gas therethroughand compressing it while being moved, an oil sump having gravityconnection with the 13 low pressure side and a second oil sump havinggravity connection with the high pressure side, a two part gear pumpbetween the sumps, one part having pumping connection with the oil inthe low pressure sump and the other part having connection with the highpressure sump, and common means for simultaneously driving the rotor andthe gear pump.

FRANK A. WHITELEY.

REFERENCES CITED The following references are of record in the file ofthis patent:

Number 14 UNITED STATES PATENTS Name Date Wisdom Jan. 21, 1913 DiffingerFeb. 16, 1926 Cozette Dec. 14, 1926 Oliver July 5, 1927 Johnson Oct. 31,1939 Kucher Feb. 25, 1941 Meyerhoefer May 13, 1941 Whiteley July 4, 1944

